Đang chuẩn bị liên kết để tải về tài liệu:
CYANIDE in WATER and SOIL: Chemistry, Risk, and Management - Chapter 21

Sự hấp phụ của các loài xyanua từ nước vào giai đoạn rắn không đã được nghiên cứu rộng rãi, nhưng nó được biết rằng các loài cyanide và kim loại-cyanide tự do phản ứng bề mặt triển lãm với một số khoáng sản chất rắn và than hoạt tính. Từ các nghiên cứu giới hạn đã được thực hiện, nó xuất hiện cyanide (HCN, CN) có rất ít hoặc không có xu hướng để hấp thụ các khoáng chất vô cơ như oxit sắt [1] và cát [2],. | 21 Separation Technologies for Treatment of Cyanide David A. Dzombak Rajat S. Ghosh George M. Wong-Chong and John R. Smith CONTENTS 21.1 Adsorption Technologies . 413 21.1.1 Activated Carbon. 414 21.1.2 Synthetic Ion Exchange Resin. 418 21.1.3 Activated Alumina. 421 21.2 Precipitation Technologies. 423 21.2.1 Iron-Cyanide Precipitation Reactions. 423 21.2.2 Iron-Cyanide Precipitation Processes. 424 21.2.3 Operation and Regulatory Issues. 428 21.3 Air Stripping . 429 21.3.1 Counter-Current Air Stripping. 429 21.3.2 Recovery and Reuse of Cyanide in Hydrometallurgical Gold Mining . 430 21.4 Summary and Conclusions . 434 References. 435 While low-temperature and thermal oxidation technologies are employed most commonly for destruction of cyanide species in water soils sludges and solids see Chapters 20 and 22 physicalchemical separation of cyanide species is an alternative sometimes less expensive treatment approach for cyanide-bearing waters. This is especially the case for treatment of strong metal-cyanide species which often are not as readily oxidized as free cyanide and weak-acid-dissociable WAD cyanide. The reactivity of cyanide species on certain kinds of solid surfaces activated carbon in particular is exploited for adsorptive removal from water. In addition the ability of cyanide to react with certain metals especially iron to form relatively insoluble solids is exploited for precipit-ative removal of free and metal complexed cyanide. Finally air stripping can be used to remove free cyanide from water as HCN is a volatile species. In this chapter we examine adsorption precipitation and air stripping treatment approaches that have been used to treat various cyanide-bearing waters. 21.1 ADSORPTION TECHNOLOGIES Adsorption of cyanide species from water onto solid phases has not been extensively studied but it is known that free cyanide and metal-cyanide species exhibit surface reactivity with certain mineral solids and with activated carbon. From the limited .